Framingham-based Ameresco Inc. released its 2012 financial results, and they “were below our expectations,” CEO George P. Sakellaris said in a press release, adding that “we remain encouraged by the progress we have made” on several fronts. Fourth-quarter revenue was $156.6 million, down 16.9 percent from a year earlier; net income was $5.1 million, down 39.7 percent. For the full year, revenue fell 13.3 percent to $631.2 million. Net income fell 45.1 percent to $18.4 million.